<!DOCTYPE html>
 	<html lang="en">
 	
 	<head>
 	    <meta charset="UTF-8">
 	    <meta name="viewport" content="width=device-width, initial-scale=1.0">
 	    <title>bootstrap 练习</title>
 	    <link href="../09/css/main.css" rel="stylesheet">
 	    <style>
 	        /* 响应式布局的基础 */
 	        @media (min-width: 576px) .container {
 	            max-width: 540px;
 	        }
 	
 	        .row div {
 	            border: 1px red dashed;
 	        }
 	
 	    </style>
 	
 	</head>
 	
 	<body>
 	    <nav class="navbar navbar-expand-lg navbar-light bg-light">
 	        <a class="navbar-brand" href="#">Navbar</a>
 	        <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent"
 	            aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
 	            <span class="navbar-toggler-icon"></span>
 	        </button>
 	
 	        <div class="collapse navbar-collapse" id="navbarSupportedContent">
 	            <ul class="navbar-nav mr-auto">
 	                <li class="nav-item active">
 	                    <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
 	                </li>
 	                <li class="nav-item">
 	                    <a class="nav-link" href="#">Link</a>
 	                </li>
 	                <li class="nav-item dropdown">
 	                    <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button"
 	                        data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
 	                        Dropdown
 	                    </a>
 	                    <div class="dropdown-menu" aria-labelledby="navbarDropdown">
 	                        <a class="dropdown-item" href="#">Action</a>
 	                        <a class="dropdown-item" href="#">Another action</a>
 	                        <div class="dropdown-divider"></div>
 	                        <a class="dropdown-item" href="#">Something else here</a>
 	                    </div>
 	                </li>
 	                <li class="nav-item">
 	                    <a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
 	                </li>
 	            </ul>
 	            <form class="form-inline my-2 my-lg-0">
 	                <input class="form-control mr-sm-2" type="search" placeholder="Search" aria-label="Search">
 	                <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
 	            </form>
 	        </div>
 	    </nav>
 	
 	    <main>
 	        <section>
 	            <div class="jumbotron container">
 	                <h1 class="display-4">Hello, world!</h1>
 	                <p class="lead">This is a simple hero unit, a simple jumbotron-style component for calling extra
 	                    attention to featured content or information.</p>
 	                <hr class="my-4">
 	                <p>It uses utility classes for typography and spacing to space content out within the larger container.
 	                </p>
 	                <a class="btn btn-primary btn-lg" href="#" role="button">Learn more</a>
 	            </div>
 	        </section>
 	        <section>
 	            <h2>container 容器</h2>
 	            <div class="container">大幅度发</div>
 	        </section>
 	        <section>
 	            <h2>栅格系统</h2>
 	            <div>
 	                <div class="container">
 	                    <div class="row">
 	                        <div class="col-md">
 	                            One of three columns
 	                        </div>
 	                        <div class="col-md">
 	                            One of three columns
 	                        </div>
 	                        <div class="col-md">
 	                            One of three columns
 	                        </div>
 	                        <div class="col-md">
 	                            One of three columns
 	                        </div>
 	                        <div class="col-md">
 	                            One of three columns
 	                        </div>
 	                        <div class="col-md">
 	                            One of three columns
 	                        </div>
 	                        <div class="col-md">
 	                            One of three columns
 	                        </div>
 	                        <div class="col-md">
 	                            One of three columns
 	                        </div>
 	                        <div class="col-md">
 	                            One of three columns
 	                        </div>
 	                        <div class="col-md">
 	                            One of three columns
 	                        </div>
 	                        <div class="col-md">
 	                            One of three columns
 	                        </div>
 	                        <div class="col-md">
 	                            One of three columns
 	                        </div>
 	                        <div class="col-md">
 	                            One of three columns
 	                        </div>
 	                        <div class="col-md">
 	                            One of three columns
 	                        </div>
 	                    </div>
 	                </div>
 	                <div class="container">
 	                    <div class="row">
 	                        <div class="col">ssdsd</div>
 	                        <div class="col-sm-6">sdsdsd</div>
 	                        <div class="col">sdsds</div>
 	                    </div>
 	                </div>
 	                <h3>列居中</h3>
 	                <div class="container-fluid">
 	                    <div class="row justify-content-center">
 	                        <div class="col-4">
 	                            One of two columns
 	                        </div>
 	
 	                    </div>
 	                </div>
 	                <h3>列偏移</h3>
 	                <div class="container">
 	                    <div class="row">
 	                        <div class="col-4 offset-3">
 	                            <h3>栅格嵌套</h3>
 	                            <div class="container">
 	                                <div class="row">
 	                                    <div class="col-4">ddd</div>
 	                                    <div class="col-4">ddd</div>
 	                                    <div class="col-4">ddddd </div>
 	                                </div>
 	                            </div>
 	
 	                        </div>
 	                    </div>
 	                </div>
 	
 	            </div>
 	
 	        </section>
 	
 	    </main>
 	    <footer></footer>
 	
 	</body>
 	
 	</html>
